Joystick base



FIG. 1 is a front-right-top perspective view of a joystick base, showing my new design;

FIG. 2 is a front view thereof, the opposite side view being a mirror image;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a joystick base, as shown and described. 